Method and apparatus for hanging a well casing in a well bore



Jan. 24, 1967 L. E. WILLIAMS ETAL METHOD AND APPARATUS FOR HANGING A WELL CASING IN A WELL BORE Filed May 28, 1963 5 Sheets-Sheet 1 Leonard E. W//// 04fil 7 s' m w M {M M 0% n w R cw M 2 w J w 0 Z Jan. 24, 1967 L. E. WILLIAMS ETAL METHOD AND APPARATUS FOR HANGING A WELL CASING IN A WELL BORE Filed May 28, 1963 5 Sheets-Sheet 2 Leo/70rd E l/V////0m r 100/; /l Fey 0n INVENTORJ ATTOR/VE VJ L. E. WILLIAMS ETAL 3,

Jan. 24, 1967 METHOD AND APPARATUS FOR HANGING A WELL GASING IN A WELL BORE 5 Sheets-Sheet 5 Filed May 28, 1965 Leo/70rd W/ omu 10am M. Raga/7 TORS w ATTO/P/VE m INVEN Jan. 1967 L. E. WILLIAMS ETAL. 3,

METHOD AND APPARATUS FOR HANGING A WELL CASING IN A WELL BORE 5 Sheets-Sheet 4 Filed May 28, 1963 A TTOR/VE m Jan. 24, 1967 L. E. WILLIAMS ETAL 3, 99,954

METHOD AND APPARATUS FOR HANGING A WELL CASING IN A WELL BORE 5 Sheets-Sheet 5 Filed May 28, 1965 L 60/70/6/ f. W/ ///C7/77J Lou/J M Rey INVENTORS ATTORA/EVJ United States Patent METHOD AND APPARATUS FOR HANGING A WELL CASING IN A WELL BORE Leonard E. Williams and Louis M. Regan, Houston, Tex.,

assignors to Cameron Iron Works, Inc., Houston, Tex., a corporation of Texas Filed May 28, 1963, Ser. No. 283,780

18 Claims. (Cl. 166-35) This invention relates generally to a method and apparatus for hanging a well casing in a well bore during the running of the casing string. More particularly, it relates to an improved method and apparatus for suspending the casing from a casing head and sealing off the annular space between the casing and bore of the head when the head is located at a relatively inaccessible location, such as at an underwater level in the drilling and completion of an offshore well; and, in accordance with one aspect of this invention, when the casing becomes stuck in the well bore.

In the ordinary drilling and completion of an oil or gas well, the well casing is lowered to the desired depth within the well bore and suspended therein by means of a mandrel or so-called boll weevil casing hanger which is threaded on its lower end for connection to the upper end of the top joint of casing and which has an outer surface for landing upon the seat. However, in the event the casing becomes stuck in the well bore before reaching the desired depth, and the upper end of its top joint is too far above the seat to permit the casing to be hung with a mandrel type of hanger, the operator mayuse another type of casing hanger which includes an assembly carrying slips on its inner surface and adapted to be wrapped around the casing so that it may slide downwardly therealong to land its outer surface on the bowl of the casing head. Thus, when a strain is placed on the casing and then slacked Off, the slips are caused to grip and thereby suspended it at a level beneath its upper end. Even when the casing is not stuck, some operators may nevertheless prefer to use the slip type suspension.

When the casing is so suspended, a seal is establihed between the portion thereof above the slips and the bore of the casing head. This may be accomplished by a seal assembly separate from or forming a partof the hanger. In this latter case, the seal assembly may be connected to the slips in such a manner that it establishes the seal automatically in response to setting the slips. In either case, however, the seal assembly includes a ring of sealing material which is split to permit it to be wrapped about and lowered down over the casing similarly to the slip assembly. Normally, the upper end of the casing will extend a considerable distance above the slip and seal assemblies so that a portion thereof must be severed and removed from within the wellhead to make room for a seat for hanging another casing within it.

The conventional wrap-around type of hanger is usable only where the slip and seal assemblies are free to slide downwardly over the casing from the level at which it is wrapped about it to the seat in the casing head. Thus, where the wellhead includes a relatively high stack above the casing head, collars between the well casing joints may prevent this type of hanger from dropping onto the seat in the casing head. Consequently, in accordance with present practices, the stack must be broken at some intermediate point to permit installation of the casing hanger, which procedure is objectionable because the operator at least temporarily loses mechanical control of the well pressure. The problem is, of course, even more acute in the case of an offshore well which is drilled and completed at an underwater level, because the seat in the casing head may be disposed below the water level a distance equal to several times the length of a joint of casing, so that the operator knows that a wrap-around type of hanger will not slip downwardly over the casing onto the seat in the casing head.

It has therefore been proposed to provide wellheads for such wells with auxiliary hangers made up of slip segments which are carried within the casing head so that they may be launched into the bore of the head and onto the seat therein for suspending a casing in the event it becomes stuck. However, this apparatus requires a large original investment, because the wellhead must be equipped with it at the time the well is being drilled even if the casing does not become stuck and the special hanger is therefore not used. Furthermore, the casing head of such a wellhead must be increased in height in order to accommodate the slip segments carried therein, which may cause a real problem in the case of onshore wells where the wellhead is disposed beneath the derrick floor, and which in any case increases the moments due to loads on the wellhead. Still further, it may be found that the teeth on the inner surfaces of the slips of these hangers become fouled or damaged to such an extent that they do not firmly and securely grip the casing when launched into the bore of the head.

It has also been the practice to patch perforated casing by severing same at a level beneath the perforation and then effectively extending its length upwardly to the wellhead by means of an overshot which is latched onto it by means of slips and then suspended in the seat of the casing head. However, this practice has required that the overshots be of special design in order to pass the smaller diameter through the casing to which the casing head is connected. Also, this type of latch on the lower end of the overshot does not provide a satisfactory seal between it and the severed casing. Still further, the upper end of the severed casing is exposed to the drill bit during the drilling of additional hole through the patched casing, and this can result in very serious damage to the casing as well as the overshot latched to it.

It is an object of this invention to provide a method of and apparatus for suspending a casing from and sealing it with respect to a casing head which as inaccessible from the upper end of the wellhead and wherein a mandrel type suspension is either not preferred or impossible due to sticking of the casing, such method and apparatus permitting the casing to be so hung without a large original investment or an increase in the height of the wellhead and with assurance that the casing will be firmly and securely suspended.

Another object is to provide such a method which does not require the installation of special equipment prior to the suspension, and thus not unless and until a casing becomes stuck, and wherein such conventional equipment as may be necessary may be kept on a standby basis for use at one of several ditferent well locations.

A further object is to provide such a method and apparatus which requires no modification to the construction of the casing head so that, even when the casing becomes stuck, the height of the wellhead stack need not be increased.

Still another object is to provide such a method and apparatus wherein, as in the case of casing suspensions by means of wrap-around type hangers, slips for suspending the casing need not be carried within the casing head, but instead are lowered onto the seat in the head after the casing is suspended.

A still further object is to provide such a method and apparatus which requires a minimum of specially designed parts and apparatus.

Yet a further object is to provide such a method and apparatus which is especially well suited for offshore a wells which are to be, completed at a subsurface level in that it permits the casing to be severed accurately despite the normal rise and fall of the floating vessel at the water levels a a Yet another object is to provide a method and apparatus of the character described in whicha slip assembly as well as a seal assembly is landed Within the bore of the casing head and above therseat therein, rather than within the casing below such seat to which the casing head is connected.

Another object is to provide apparatus which is especially well suited for use in the practice of this method,

and particularly a casing hanger including a slip assembly and a seal assembly which are easily and quickly run and set by means of standard tools.

A still further object is to provide such a seal assembly which is adapted to be anchored within the bore of the wellhead, but which is of such construction that it may be removed therefrom in the event it is not set in the desired manner.

These and other objects are accomplished, in accordance with this invention, by a method in which the casing within the well bore is severed at a level between the seat in the casing head and the casing collar next above it, the severed portion of casing is removed from within the wellhead bore, a slip assembly is lowered onto the seat and about the casing, and a strain is pulled on the casing and then relieved to cause the slip to grip and thereby suspend the casing. In order to complete the hanging of the casing, a seal assembly is landed in the bore of the wellhead above the seat to seal off the space between it and the remaining portion of the casing, this seal assembly being lowered with or subsequent to the landing of the slip assembly. In the illustrated embodiment of the invention, the casing is first severed and the slip assembly and seal assembly are lowered about the remaining portion of the casing so that they have no collars to pass ,over.

In some cases, especially in onshore wells, it may be found that the casing canbe severed with suflicient accuracy that its upper end is at a proper level intermediate the portion thereof to be sealed with respect to the wellhead bore and the seat to be mounted above it for hanging the next casing. However, this is not possible in most cases, particularly in view of the difiiculty in making accurate measurements in the case of offshore wells where the wave action will causethe vessel from which the cutting tool is run to rise and fall. Thus, inaccordance with a preferred practice of the present invention, the casing is again severed after it is suspended, this time at a more accurate predetermined level above the seat of thercasing head, and the additional severed portion of the casing is removed from within the bore of the well head. i More particularly, a cutting tool is lowered into the bore and landed on the slip assembly in order to position it for severing the casing at the desired predetermined level, and the additional severed portion of the casing is removed from within the wellhead bore. Thus, when a seal assembly is then lowered into the bore and landed therein, preferably upon the slip assembly, the operator is assured that it will seal between the casing and bore of the casing head and yet not interfere with the seat for hanging the next casing. In like fashion, when the seal assembly is lowered with the slip assembly, the operator can, by means of this additional severing of the casing, be assured that the upper end of the remaining casing will be below the next hanger seat. In accordance with the preferred embodiment of the present invention, such seat is disposed on the upper end of the seal assembly and, when lowered and landed in the bore with the seal assembly, provides a guide during the drilling of additional hole.

' Since the conventional external type of easing cutter will not pass over collars between the casing joints, the casing is initially severed by means of an internal type of cutting tool which is run into the casing and anchored thereinfto dispose its cutting edges opposite the desired level in the casing. In the illustrated method, the cutting tool and pipe on which it is run maybe left in anchored position within the casing as the slip assembly is landed on the seat of the casing head, and then raised and lowered to place the desired strain in the casing and cause the slip assembly to suspend the casing. When this'pipe'is left within the casing during this interim, it is also useful in guiding the slip assembly as it is lowered into and raised from the bore of the wellhead, particularly in that it maintains the remaining portion of the casing at least approximately centered in the bore. Alternatively, of course, the cutting tool may be removed from within the wellhead bore during running of the slip assembly, and then run'back in and anchored to the casing in order to set the slips.

In the drawings, wherein like reference characters are used throughout to designate like parts:

FIG. 1 is a longitudinal sectional view of an ofishore well including an outer casing cemented in place within the well bore and a wellhead connected above the outer casing at the underwater level, and wherein an inner casing which has been stuck within the well bore extends upwardly through the outer casing and bore of the wellhead;

FIG. 2 is a view similar to FIG. 1, but wherein a cutting tool has been run into the stuckcasing and anchored therein at a level for severing same above the seat in the casing head and below the casing collar next above it;

FIG. 3 is a similar view in which the casing has been so severed by the cutting tool and the severed portion of the casing removed from withinn the bore of the wellhead, and wherein a slip assembly has been lowered therein and landed on the seat of the casing head by means of an overshot;

FIG. 4 is another similar view, but in which the overshot has been removed and a strain taken on the casing and relieved to cause it to be suspended from the slip assembly;

FIG. 5 is another similar view in which another cutting tool has been lowered into the bore of the wellhead and actuation of the slip anchor of the seal assembly;

landed on the slip assembly and operated to sever the remaining casing at a predetermined level above the seat in the casing head; a

FIG. 6 is still another similar view, but in which the additional severed portion of the casing as well as the cutting tool have been removed from the bore of the wellhead and the seal assembly has been lowered into place to seal between the casing and the bore of the casing head and dispose a seat above the upper end of the casing for hanging another casing;

FIG. 7 is an enlarged sectional view, broken away in part, of the slip assembly and means shown in FIG. 3 for lowering it onto the casing'head seat;

FIG. 8 is a partialview similar to FIG. 7, but showing a modification of the slip assembly having a seal assembly connected thereto for landing therewith;

FIG. 9 is an enlarged sectional view of the seal assembly of FIG. 7landed upon and anchored to the slip assembly, but prior to compression of the seal rings and FIG. 10 is a view similar to FIG. 9, but in which the seal rings have been compressed and the slip anchor ac; tuated so as to establish a seal between the casing and bore of the casing head and anchor the seal assembly in-, cluding the seal rings to the bore of the wellhead;

FIG. 11 is an elevational view of part ofthe anchor of the seal assembly to the slip assembly, as seen along broken line 11--11 of FIG. 9;

FIG. 12 is a cross-sectional view of part of the slip assembly, as seen along broken line 12-12 of FIG. 9;' and r FIG. 13 is an enlarged sectional view form of seal assembly. 7 i v l.

With reference now to the details of the above-described drawings, the offshore well shown in. FIGS. l to 6 includes a well bore 20 drilled into the underwateriground level 21 and having an outer casing 22 anchored therein of an alternative by a column of cement 23. The upper. end of the cement column is contained by means of a conical base 24 on the lower end of wellhead 25 welded to the upper end of outer casing 22. In accordance with conventional practice, the wellhead 25 includes a casing head 27 at its lower end, one or more blowout preventers 28 thereabove, and a tubular conductor (not shown) above the preventers and extending to a vessel at the Water level from which the drilling operations are performed.

As is also common in the case of wells which are drilled and completed at an underwater level, there are two or more lines or cables 29 which extend downwardly from a vessel at the water level for connection with a frame 30 carried by and extending outwardly from the wellhead. These lines are, of course, useful in guidably raising and lowering equipment with respect to the well. For example, they may be employed in the connection and disconnection of the preventers 28 with respect to the casing head 27. For this purpose, and as shown in FIG. 1, dogs 28a may be carried about a flange on the lower end of the preventers for swinging into and out of latching position over a flange on the upper end of the head, and a sleeve 28b may be arranged about the dogs for so swinging them as the sleeve is raised and lowered. The sleeve is connected to radially extending arms 280 which are suspended from the lower ends of cables 28d and have guide sleeves 28e guidably slid'able over the lines 29 as the cables 28d are taken up and paid out by means of suitable apparatus at the water level. Apparatus of this type is shown and described in more detail in a copending application, Serial No. 746,997, filed July 7, 1958 by Arthur G. Ahlstone and Marvin R. Jones, and assigned to the assignee of the present application.

The casing head 25 has a conical seat 31 intermediate an upper enlarged bore 32 and a lower reduced bore 33. The upper bore forms a continuation of the bore 34 through the p-reventcrs 28 as well as the tubular conductor (not shown), while the lower reduced bore forms a substantial continuation of the inner diameter of the outer casing 22. As is conventional in casing heads, there is a valve 35 connecting with the lower bore 33 of the head beneath the seat 31.

As shown in FIG. 1, an inner casing 36 has become stuck in the well bore as it was run through the outer casing 22. This sticking may occur due to any number of factors, such as heaving shale, pressure difierential sticking, etc. At any rate, the operator cannot lower it to dispose its upper end at a level which will permit a mandrel type casing hanger to be connected thereto and landed upon the seat 31.

Furthermore, there will ordinarily be one or more casing collars 37 intermediate the casing head seat 31 and the upper end of the wellhead or the tubular connector extending to the surface to the water level. Thus, it is not possible to lower the conventional Wrap-around type of casing hanger downwardly along the inner casing 36 onto the seat 31. It is also obvious that, in the case of this offshore well completed at an underwater level, it would not be possible to break the stack so as to insert a wrap-around type of hanger between the seat of the easing head and the first collar 37 thereabove.

Still further, even if the well were completed at an onshore location, it could be found that the stack was so high that the portion of the casing intermediate the upper end of the stack and the casing head seat 31 was not free of collars. Even though it might be possible to break the stack in such a situation, this is not desired for reasons previously mentioned. Thus, in any case, this invention contemplates that it will be necessary or at least quite desirable to hang the stuck casing 36 from the seat 31 by means of a casing hanger such as described herein.

As a preliminary to the method to be described, it may be desirable to first cement the casing 36 within the well bore, in a manner well known in the art. Then, in accordance with the present invention, an internal .type cutting tool 38 is lowered into the casing 36 to a level at which its knives 39 or cutting elements aredisposed opposite a portion of the casing intermediate the seat 31 in the casing head and the collar 37 first above the seat, which level may be determined by meaiis of conventional collarlocating tools. When disposed in such position, slips 40 thereon are urged out against the casing so as to anchor it against downward movement therein and the knives 39 are urged outwardly and rotated against the casing. The cutting tool 38 may comprise any conventional construction adapted to be run upon and actuated by a drill pipe 41 or the like connected to its upper end. Thus, for example, it may be similar in construction and operation to the cutter shown and described upon page 718 of the 1962-1963 Composite Catalog of Oil Field Equipment & Services.

The severed portion of the casing is then lifted with or from above the knives 39 of the cutting tool for removal from the wellhead bore, depending on whether or not the cutting tool is also to be removed or left anchored within the stuck casing. When the latter procedure is followed, as shown in FIG. 3, a slip assembly 42 is then run downwardly into the wellhead bore and landed upon the seat 31 in the casing head about the casing 36 by means of a running tool 43. As shown in FIG. 3, and in more detail in FIG. 7, this latter tool includes an enlarged tubular member 44 having internal threads 45 about its lower end for releasable connection to external threads 46 about the upper end of the slip assembly 42. This tubular member extends upwardly to a level above the upper end of the severed casing as well as above the cutting tool 38 and is there connected to a running string 44a of reduced internal diameter, which in turn extends upwardly to the water level. As will be appreciated, the enlarged diameter of member 44 will tend to maintain the slip assembly centered in the wellhead bore; and, when the pipe 41 remains anchored to the casing 36, it can be used to at least approximately center up the casing to facilitate lowering of the slip assembly over it. When the slip assembly 42 has been landed upon the seat 31, it is urged downwardly thereagainst by means of the tool 43, which permits the threads 45 to be backed oif from the threads 46 on the slip assembly and the tool removed upwardly from within the bore of the wellhead, as can be seen from FIG. 4.

As shown in FIG. 7, as well as in FIGS. 9 to 12,.the slip assembly 42 includes an annular body 47 having an outer conical surface 48 for seating upon the seat 31 and an inner conical bowl 49 in which slips 50 are disposed for sliding downwardly and inwardly therealong. The outer diameter of the upper end of the body 47 is reduced so that the threads 46 thereon may be engaged by the threads on the lower end of the tubular member 44. The

slips 50 are circumferentially spaced apart and held within the bowl 49 by means of retainers '51, as shown in FIG. 12.

As the slip assembly 42 is moved downwardly over the upper end of casing 36, the slips 50 are free to move upwardly along the bowl 49 so that the teeth on their inner surfaces slide freely over the outside of the casing 36. However, when the slip assembly has been landed on the seat 31, and the tool 43 removed from within the well bore,,the drill pipe 41 which is anchored to the easing through the cutting tool 38 is raised to lift the casing 36 and thereby place the desired strain therein. When the pipe is then lowered a slight amount to relieve the strain, the teeth on the inner surfaces of the slips 50 are caused to grip and thereby suspend the casing, in a well known manner and as shown in FIG. 4.

The assembly 42a, shown in FIG. 8, may correspond in all respects to the slip assembly just described except that the seal rings 42b and 42c are carried on the inner and outer surfaces, respectively, of the annular body 47. Thus, when the combined slip and seal assembly is lowered upon tubular member 44 onto the ring 420 will seal against the bore 32 above the seat the seat in the casing head,

and the ring 42b will seal about the stuck casing.

As previously mentioned, it may be found that the upper end of the remaining casing portion is at a level which will not interfere with the seat for the next hanger,

or, in the case of the embodiment of FIG. 7, at such a level that a seal may also be established between it and the bore of the wellhead. However, it will normally be .found that this first cut of the casing it not sufficiently accurate to permit these further steps in the hanging of the casing 36, so that, and again as previously described, it is necessary to more accurately sever same for the purposes mentioned.

Thus, at this stage of the method, the drill pipe 41 on the casing cutter is manipulated to release the anchoring dogs'40 thereof and retract the cutting knives so that the end of the cutting tool 52 carries a spacer 55 which is landed upon the upper endof the body 47 of the slip assembly 42 so as to dispose the cutting edges of the knives 54 in the desired position. 1 V

The cutting tool 52 may also be of conventional construction, in this case similar to that shown on page 716 of the 1962-1963 Composite Catalog of Oil Field Equipment & Services. As shown in such publication, this type of cutter includes a means for anchoring the tool to the casing 36 to be cut to permit an upwardly strain to be taken thereon. In this way, the force of a spring 56 may be released from urging the cutting edges of the knives 54inwardly, whereby thecutting tool may be rotated by means of the running string 53 so as to again sever the casing. Obviously, when this has been done, the external cutter 52 as well as the additional severed portion of the casing need only be removed upwardly by-means of the running tool 53. As will be noted from FIG. 5, the

- outer diameter ofthe running tool 53 fits rather closely within the bore of the wellhead which, similarly to the enlarged outer diameter of the tubular member 44 of tool ;ing onto the upper end of the seal assembly by means of dogs 59 or the like adapted to be received in an annular groove 60. More particularly, the latching mechanism is of a type which, upon manipulation of the running tool, permits the seal assembly to be lowered and then rotated in a desired manner prior to release of the running tool from the seal assembly.

For reasons to be described below, the lower end of the seal assembly is preferably anchored to the upper end of the slip assembly. For this purpose, and as shown -in FIGS. 9 andv 11 illustrating the preferred embodiment .of the seal assembly, the upper end of the'body 47 of the slip assembly. has several J-shaped slots 61 therein for receiving similarly shaped hooks 62 depending from the bottom end of the seal assembly. More particularly, and

as shown in FIG. 11, the lower end of the hook 62 is of a width adapted to pass downwardly through the open upper end of the slot 61 when the seal assembly is properly oriented with respect to the slip assembly. Then, when this alignment of "the hook within the slot has been made, the seal assembly may be rotated by means of the runthe overhang 63 of the slot 61, as shown in FIG. 11.

ining t0ol'58 so as to dispose the end of'the hook beneath the casing head 27 for sealing with respect thereto. lady to the ring 71, in the relaxed position shown in FIG.

As best shown in, FIGS. 9 and 10, the seal assembly 57 has an annular body made :up of a lower part 64 from Which'the hooks 62 depend, an intermediate part 65, and an upper part 66. The intermediate body part 65 has an outwardly disposed lower portion 67 which is threadedly connected at 68 to the lower body part 64 and an inwardly disposed upper portion 69 which is threadedly connected at 70 to the upper body part 66. The seal assembly 57 also includes an inner seal ring 71 having its opposite ends held between a downwardly facing shoulder 72-on the intermediate body part 65 and an upwardly facing shoulder 73 on lower body part 64. More particularly, the seal ring 71 is carried about the outwardly disposed lower portion 67 of the body part '65 so that its inner surface is disposed, upon anchoring of the lower end of the assembly to theseat assembly, for sealing about the upper portion of casing 36. In the position of the body parts shown in FIG. 9, the seal ring is relaxed so that the assembly is free to slide over the casing 36. However, upon rotation of the intermediate body parts 65 in a direction to move it downwardly with respect to body part 64 from the, position of FIG. 9 to that of FIG. 10 will compress the seal ring 71 outwardly to establish the seal about the upper end of thecasing 36.

The seal assembly also includes an outer seal ring 74 having its opposite ends held between the upwardly facing shoulder 75 on the body part '65 and a shoulder 76 on the lower end of a downwardly and outwardly tapering wedge 77 about body part 65 above the seal ring 74. More particularly, the outer sealrin-g 74 is carried about the inwardly disposed upper portion 69 of .the body part 65 so that its outer surface is disposed opposite the bore 32 of Simi- 9, ring 74 permits the seal assembly to slide easily through the wellhead bore. However, when the upper part 66 of the body of the sealing assembly is moved downwardly with respect to the immediate body part 65 fromthe FIG. 9 to the FIG. 10 position, and the wedge 77 is moved with such upper body part in a manner to be described,

Thus, as the upper body part is moved downwardly with respect to the intermediate body part 65, the shoulder 79 will move'the slips 78 downwardly along the taper of the edge 77 so that the wedge shoulder'76 compresses the seal 'ring 74. When the seal ring is thereby fully compressed into sealing engagement with the bore 32 of the casing head, it will provide a firm support for the wedge 77, so that further downward movement of the upper body part will finally urge the slips 78 outwardly into gripping engagement with the bore-32, thereby anchoring the seal assembly, including the seal rings 71 and 74, with respect to the casing head. i

' The upper and intermediate body parts are initially connected for rotation with one anotherby means of a shear pin 80. This connection will permit the thread 68 on the lower end of intermediate body part 65 to move downwardly along those of the lowear body parts 64 as the upper body part is first rotated by means of running tool 58. Since the lower body part is anchored to the slip assembly 42, which is held down upon the seat31 in the casing head due to its suspension of the casing 36, the

resultant force of the shoulder 72 will compress the seal for movement downwardly with respect to those on the body part 65. The resultant force due to the shoulder 79 is in a downward direction since the lower end of the intermediate body part is anchored to the lower body part by means of the threads 68. Consequently, this continued rotation of upper body part 66 upon shearing of the pin 80 will, as previously mentioned, sequentially urge the seal ring 74 into sealing engagement with the bore of the casing head and urge the slips 78 into gripping engagement with the same bore above the seal ring 74. When this has been accomplished, the running tool may be unlatched from the seal assembly, in the manner previously described, and removed from within the well bore.

One advantage afiorded by this seal assembly is that it may be recovered in the event there is a malfunction in its setting. That is, the slips 79 are not set until the IhOOkS 62 have been anchored and the seal rings 71 and 74 compressed. Furthermore, these rings are not compressed until the hooks are anchored. Thus, upon detection of a malfunction at any stage of its setting, the seal assembly may be pulled upwardly from within the bore of the wellhead.

As previously mentioned, the seal assembly 57 also ineludes a conical seat 81 on the inner surface of its body for suspending a casing to be hung within the casing 36. Thus, as shown in FIGS. 9 and 10, this seat is formed on the intermediate body part 65 above the upper end of casing 36 with the lower end of the seat 81 substantially aligned with respect to the inner diameter of the casing 36. In this manner, the seat 81 also serves as a guide for the bit in the subsequent drilling of the hole for the additional casing.

The alternative form of seal assembly 57a shown in FIG. 13 is, in many respects, similar to the seal assembly 57 shown in FIGS. 9 and 10. For example, it is made up of a body including lower body part 64a threadedly connected at 68a to intermediate body part 65a and upper body part 66a threadedly connected at 70a to the part 65a. An inner seal ring 71a is disposed between the lower and intermediate body parts similarly to the seal ring 71 of the seal assembly 57, while an outer seal ring 74a is disposed between the upper and intermediate body parts. Thus, the inner seal ring 71a is caused to seal about the upper end of casing 36 when the intermediate body part 65a is moved downwardly with respect to the lower part 64a. In this respect, the lower body part also carries a J-shaped hook 62a for anchoring it with respect to a similarly shaped slot 61 on the upper end of the body 47 of a seat assembly identical to the one previously described.

In this assembly 57a, however, anchoring slips 82 are carried freely within a tapered bowl 83 on the outer surface of the intermediate body part 65a so that they are free to engage with the bore 32 in the casing head under the influence of gravity. Thus, as distinguished from the anchoring slips 78 of the assembly 57 which are normally retracted until urged outwardly, the teeth on the inner surfaces of the slips will automatically grip the bore urged upwardly by the intermediate body part 65a. As will also be appreciated from FIG. 13, there is no shear pin between body parts 65a and 66a and the seal ring 71a is not necessarily compressed into sealing engagement prior to the outer seal ring 74a. Thus, the upper body part 66a is merely rotated by the running tool (not shown) until both such seal rings are caused to establish the desired seal.

Upon the above-described landing, anchoring and setting of either of the above-described seal assemblies, the well is ready for subsequent steps in the drilling of same, including the drilling of further hole within the well bore and through the inner casing 36, and the suspension of another casing by means of a casing hanger seatable upon seat 81 or 81a on the assembly 57 or assembly 57a, respectively.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the method and apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. A method of hanging a casing from a seat within a casing head at the lower end of the bore through a wellhead including a blowout preventer, comprising the steps of severing the casing at a level above the seat and beneath the casing collar next above the seat, removing the severed portion of the casing from within the wellhead bore, then lowering a slip assembly through the bore of the blowout preventer and and into a landed position on the seat and about the portion of the casing remaining after removal of the severed portion, pulling a strain on the casing and then relieving same to cause the slip assembly to grip and thereby suspend the casing from said seat, and establishing a seal between the bore and the remaining portion of the casing.

2. A method of hanging a casing from a seat within a casing head at the lower end of the bore through a wellhead including a blowout preventer, comprising the steps of severing the casing at a level between the seat and the casing collar next above the seat and removing the severed portion of the casing from within the wellhead bore, then lowering a slip assembly through the bore of the blowout preventer and into a landed position on the seat and about the portion of the casing, remaining after removal of the severed portion, pulling a strain on the casing and then relieving same to cause the slip assembly to grip and thereby suspend the casing from said seat, severing the remaining portion of the casing at a predeter mined level above the slip assembly and removing the additional severed portion from within the bore, and establishing a seal between the bore and the portion of the casing remaining after removal of the additional sev ered portion from within the bore.

3. A method of hanging a casing from a seat within a casing head at the lower end of a wellhead bore including a blowout preventer, comprising the steps of severing the casing at a level between the seat and the casing collar first above the seat and raising the severed portion of the casing out of the bore, then lowering a slip assembly through the bore of the blowout preventer and onto the seat about the portion of the casing remaining afiter removal of the severed portion, pulling a strain on the casing and then relieving same to cause the slip assembly to grip and thereby suspend the casing from the seat, lowering a seal assembly into a landed position within the bore and about the remaining portion of the casing, and actuating the seal assembly to establish a seal between said seal lassembly and each of the remaining casing portiorrand ore.

4. A method of hanging a casing from a seat within a casing head at the lower end of a bore through a wellhead includinga blowout preventer, comprising the steps of lowering a cutting tool into the casing and anchoring it therein at a level for severing the casing above the seat and below the next collar above the seat, operating the cutting tool to so sever the casing and raising the severed portion of the casing from within the bore, then lowering a slip assembly through the bore of the blowout preventer and into a landed position on the seat and about the portion of the casing remaining after removal of the severed pontion, pulling a strain on the casing and then relieving same to cause the slip assembly to grip and thereby suspend the oasing from said seat, and establishing a seal between the bore and the remaining portion of the casing.

5. A method of hanging a casing from a seat within a casing head at the lower end of a bore through a wellhead including a blowout preventer, comprising the steps of severing the casing art a level above the seat and beneath the casing collar next above the seat and removing the severed portion of the casing from within the wellhead bore, then lowering a slip assembly through the bore of the blowout preventer and onto the seat about the portion of the casing remaining after removal of the severed portion, pulling a strain on the casing and then relieving same to cause the slip assembly to grip and thereby suspend the casing from said seat, again severing the remaining portion of the casing at a predetermined level above the slip assembly and removing the additional severed portion from within the bore, and lowering a seal assembly into the bore and landing it therein in a position to seal between the bore and the portion of the casing remaining after removal of the additional severed portion thereof.

6. A method of hanging a casing from a seat within a casing head at the lower end of a bore through a wellhead including a blowout preventer, comprising the steps of severing the casing at a level above the seat and beneath the casing collar next above the seat, removing the severed portion of the casing from within the wellhead bore, then lowering a slip assembly through the bore of the blowout preventer and into a landed position on the seat and about the portion of the casing rema ning after removal of the severed portion, pulling a strain on the casing and then relieving same to cause the slip assembly to grip and thereby suspend said casing from said seat, lowering a cutting tool into landed position on the slip assembly within the bore and about the remaining portion of the casing to sever it at a predetermined level above said slip assembly, operating the cutting tool to so sever the remaining portion of the casing at said level and removing the additional severed portion and the cutting tool from within the bore, and lowering a seal assembly into the bore and landing it on the slip assembly in a position to seal between the bore and portion of the casing remaining after removal of said additional severed portion.

7. A method of hanging a casing from a seat within a casing head at the lower end of a bore through a wellhead including a blowout preventer, comprising the steps of lowering a cutting tool into the casing and anchoring it therein at :a level for severing the casing above the seat and below the next collar above the seat, operating the cutting tool to so sever the casing and raising the severed portion of the casing from within the bore, then lowering a slip assembly through the bore of the blowout preventer and onto the seat about the portion of the casing remaining after removal of the severed portion, pulling a strain on the casing and then relieving same to cause the slip assembly to grip and thereby suspend the casing from said seat, lowering a cutting tool into the bore and landing it on the slip assembly and about the casing in position to again sever it at a predetermined level thereabove, operating the last-mentioned cutting tool to so sever the casing and removing same with the additional severed casing portion from within the bore, and lowering a seal assembly into the bore and connecting it to the slip assembly to seal between the bore and the remaining portion of the casing.

8. Apparatus for use in hanging a casing from a seat within a casing head at the lower end of a bore through a wellhead, comprising a slip assembly including a unitary annular body having a surface on its outer side for landing upon the casing head seat and carrying slips on its inner side for movement into gripping engagement with the casing when the slip assembly body is lowered through the bore and onto the seat in the casing head and about the casing, means for lowering the body into landed position comprising an elongate tubular member having an inner diameter adapted to move downwardly over the casing within the bore and means on its lower end for releasable connection with the slip assembly body, means for lowering the tubular member within the bore of the wellhead and releasing its connection with the slip assembly body when said body is landed on the seat, and additional means on the upper end of the slip assembly body for anchoring an annular seal assembly thereto upon lowering of said seal assembly through the bore and over the casing. I

9. Apparatus for use in hanging a casing from a seat within a casing head at the lower end of :a bore through a wellhead, comprising a combination slip and seal assembly including a unitary annular body having -a surface on its outer side for landing upon the casing head and slips carried on its inner side for sliding downwardly and inwardly therealong into gripping engagement with the casing when the body is lowered through the bore and onto the seat in the casing head and about the casing, means carried by the body for sealing with the bore above the seat and with the casing, means for lowering the body into landed position comprising an elongate tubular member having an inner diameter adapted to move downwardly over the casing within the bore and threads on its lower end for releasable threaded connection to the body above the slips, and means for lowering the tubular member within the bore of the Wellhead and releasing its threaded connection with the body when said body is landed on the seat.

10. Apparatus for use in hanging a casing from a seat within a casing head at the lower end of a bore through a wellhead, comprising a unitary annular body adapted to be lowered through the bore about the casing and having an outer surface for landing upon the casing head seat and a bowl on its inner surface, slips carried within the bowl for sliding therealong into gripping engagement with the casing when the body is landed upon the seat in the casing head and about the casing, external threads about the upper end of the body above the slips, and means for lowering the body into landed position comprising an elongate tubular member having internal threads about its lower end for releasable connection with the external threads on the body and extendible upwardly through the bore and about the casing, and means for lowering the tubular member within the bore and rotating it when the slip body is landed on the seat so that the tubular member may be backed oif from the slip body.

11. Apparatus of the character defined in claim 10, including means carried by the body for sealing between it and each of the casing and bore above the casing head seat.

12. Apparatus for use in hanging a casing from a seat within a casing head at the lower end of a bore through a wellhead, comprising an annular slip and seal assembly adapted to be lowered through the bore into a landed position and about the casing, and including a unitary slip body having a conical bowl on its inner side and slips carried within the bowl for sliding downwardly and inwardly therealong into gripping engagement with the casing, and means for sealing between the casing and bore when the assembly is landed, said seal means including a body separate from the slip body and having annular sealing surfaces which are norm-ally retracted when lowered into a landed position, and means operable by a tool extending downwardly into the bore for expanding said sealing surfaces into sealing engagement with the casing and bore.

13. Apparatus of the character defined in claim 12, wherein each of the slip body and seal means body has threads thereon for connection 'with a means for lowering it within the bore.

14. Apparatus of the character defined in claim 12, including slips carried on the outer surfiace of the body of the seal means for anchoring same against upward movement within the well bore.

15. Apparatus for use in hanging a casing from a seat within a casing head at the lower end of :a bore through a wellhead, comprising an annular assembly lowerabl through the bore and onto the seat about the casing, said assembly including a body having a conical bowl on its inner side and slips slidable downwardly and inwardly along the bowl for movement into gripping engagement with the casing to suspend same, means for sealing between the casing and bore, and a seat on the sealing means disposable above the casing to support a casing hanger therefrom.

16. Apparatus of the character defined in claim 15, wherein the body is separate from the sealing means and has a surface thereon for landing on the seat about the casing head, and including means for anchoring the sealing means to the body.

17. Apparatus of the character defined in claim 15, including means for anchoring the assembly against upward movement within the bore.

18. An assembly for sealing between a casing and the bore of a wellhead in which the casing is disposed, comprising an annular body adapted to be disposed in the annulus between the casing and bore, said body com prising a lower part having means on its lower end for anchoring it against upward movement within the annulus, an intermediate part downwardly movable with respect to the lower part, an upper part adapted to be moved downwardly with respect to the intermediate part, inner and outer seal rings between the lower and intermediate body parts and between the intermediate and upper body parts, respectively, for sealing against said casing and bore, means connecting the intermediate part to the upper part for moving downwardly therewith and relative to the lower part until the inner seal ring is compressed into sealing engagement with the inner member and then freeing the upper part to move downwardly with respect to the intermediate part for compressing the outer seal ring into sealing engagement with the outer member, slips on the outer surface of the body intermediate the upper body part and the outer seal ring for sliding movement therealong into gripping engagement with the bore to anchor said body against u ward movement with respect to the bore when the outer seal ring is compressed, and a seat on the inner surface of the body above the inner seal ring for disposal above the upper end of the casing when the body is anchored in the annulus.

References Cited by the Examiner UNITED STATES PATENTS 2,134,311 10/1938 Minor et al 166-46 2,220,359 11/1940 Ischappat 166-88 2,228,555 1/1941 Baker 166-47 X 2,304,793 12/1942 Bodine 166-35 2,771,956 11/1956 Johnson 166-88 2,970,646 2/1961 Knapp et a1 166-46 3,098,525 7/1963 Haeber 166-66.5 3,096,999 7/1963 Ahlstone et a1. 16666.5 X 3,104,708 9/1963 Orr et al 16646 3,115,933 12/1963 Haeber 166-66.5 3,127,197 3/1964 Kretzschmar 166-75 3,137,348 6/1964 Ahlstone et a1. 166-6 3,163,217 12/1964 Haeber 166-14 3,204,695 9/1965 Murray 16655.6

CHARLES E. OCONNELL, Primary Examiner.

C. D. JOHNSON, J. A. LEPPINK,

Assistant Examiners. 

1. A METHOD OF HANGING A CASING FROM A SEAT WITHIN A CASING HEAD AT THE LOWER END OF THE BORE THROUGH A WELLHEAD INCLUDING A BLOWOUT PREVENTER, COMPRISING THE STEPS OF SEVERING THE CASING AT A LEVEL ABOVE THE SEAT AND BENEATH THE CASING COLLAR NEXT ABOVE THE SEAT, REMOVING THE SEVERED PORTION OF THE CASING FROM WITHIN THE WELLHEAD BORE, THEN LOWERING A SLIP ASSEMBLY THROUGH THE BORE OF THE BLOWOUT PREVENTER AND AND INTO A LANDED POSITION ON THE SEAT AND ABOUT THE PORTION OF THE CASING REMAINING AFTER REMOVAL OF THE SEVERED PORTION, BPULLING A STRAIN ON THE CASING AND THEN RELIEVING SAME TO CAUSE THE SLIP ASSEMBLY TO GRIP AND THEREBY SUSPEND THE CASING FROM SAID SEAT, AND ESTABLISHING A SEAL BETWEEN THE BORE AND THE REMAINING PORTION OF THE CASING.
 8. APPARATUS FOR USE IN HANGING A CASING FROM A SEAT WITHIN A CASING HEAD AT THE LOWER END OF A BORE THROUGH A WELLHEAD, COMPRISING A SLIP ASSEMBLY INCLUDING A UNITARY ANNULAR BODY HAVING A SURFACE ON ITS OUTER SIDE FOR LANDING UPON THE CASING HEAD SEAT AND CARRYING SLIPS ON ITS INNER SIDE FOR MOVEMENT INTO GRIPPING ENGAGEMENT WITH THE CASING WHEN THE SLIP ASSEMBLY BODY IS LOWERED THROUGH THE BORE AND ONTO THE SEAT IN THE CASING HEAD AND ABOUT THE CASING, MEANS FOR LOWERING THE BODY INTO LANDED POSITION COMPRISING AN ELONGATE TUBULAR MEMBER HAVING AN INNER DIAMETER ADAPTED TO MOVE DOWNWARDLY OVER THE CASING WITHIN THE BORE AND MEANS ON ITS LOWER END FOR RELEASABLE CONNECTION WITH THE SLIP ASSEMBLY BODY, MEANS FOR LOWERING THE TUBULAR MEMBER WITH THE BORE OF THE WELLHEAD AND RELEASING ITS CONNECTION WITH THE SLIP ASSEMBLY BODY WHEN SAID BODY IS LANDED ON THE SEAT, AND ADDITIONAL MEANS ON THE UPPER END OF THE SLIP ASSEMBLY BODY FOR ANCHORING AN ANNULAR SEAL ASSEMBLY THERETO UPON LOWERING OF SAID SEAL ASSEMBLY THROUGH THE BORE AND OVER THE CASING. 